Understanding elementary shapes

• The unit of measurement of an angle is degree

• 1°= 60′

• 1minute= 60 seconds

•  One complete rotation is 360°

• The angle between the North directions and East is 90°

• The protractor is an instrument used to measure angles and draw angles of required magnitude.

• Acute angle – It’s measure is more than 0° and less than 90°

• Obtuse angle – It’s measure is more than 90° and less than 180°

• An angle equal to 2 right angles, I.e, whose measure is 280° is called a straight angle.

• A reflex angle is an angle which is larger than a straight angle. It’s measure is more than 180° and less than 360°

• Two lines that have only one point in common are called intersecting lines.

• Two lines in the same plane they do not intersect are called parallel lines. The distance between two parallel lines is the same everywhere.